This disclosure relates to heat storage members for canisters. The heat storage members and phase-change material are housed in the canister configured to adsorb fuel vapor, which has vaporized in a fuel tank. The phase-change materials decrease temperature alteration in the canister by using latent heat generated during solidification or melting.
Japanese Laid-Open Patent Publication No. 2009-215938 belonging to the applicant of this application discloses heat storage members. In Japanese Laid-Open Patent Publication No. 2009-215938, for example, hexadecane (C16H34) having the melting point at 18° C. is used as the phase-change material housed in the sealed container. This phase-change material changes to liquid at its melting point (and above the melting point). Because its volume increases during the phase-change from solid into liquid, a space capable of accepting increase in volume of the phase-change material is provided between an inner surface of the sealed container and a surface of the phase-change material.
However, when the phase-change material described in Japanese Laid-Open Patent publication No. 2009-215938 melts, it completely becomes liquid. Thus, when inertial force referred to as G caused by acceleration and deceleration or cornering during driving is applied to the phase-change material, it moves in the sealed container such that the contact location and contact area between the inner surface of the sealed container and the phase-change material fluctuates. Therefore, thermal conductivity from an outer space around the heat storage member to the phase-change material via the sealed container varies, so that a heat storage effect (i.e., an effect of decrease in temperature alteration) is unstable.
Further, because Japanese Laid-Open Patent Publication No. 2009-215938 is based on the premise that the phase-change material completely becomes liquid when it melts, the space capable of accepting increase in volume of the phase-change material is provided between the inner surface of the sealed container and the surface of the phase-change material. Accordingly, there is always a part of the sealed container not contacting the phase-change material, so that it is difficult to efficiently conduct heat from the outer space to the phase-change material throughout the heat storage member. Accordingly, there is a need for improved heat storage members for the canister.